@warped-rudi Thanks a lot for the contribution. The BGR->RGB is breaking change. I'll will discuss it with core team and return back. We also have NativeView class based on VideoCapture. Please add color space setter there to prevent wrong colors.

I think the cause of the problem is the following: From this code here I gather, that the intention is to produce BGR. The reason why we get something like RGB instead is, that the source format is not NV21, but NV12. This is backed by line 514. AndroidMediaNdkVideoWriter basically uses the same hardware accelerator and it's quite unlikely, that different formats get used for encoding and decoding.

We also have NativeView class based on VideoCapture. Please add color space setter there to prevent wrong colors.

I can't find this class. Where is it?

https://github.com/opencv/opencv/blob/4.x/modules/java/generator/android-24/java/org/opencv/android/NativeCameraView.java

/cc @komakai

O.K. I see. But this code uses a camera, which means that it instantiates 'AndroidCameraCapture' instead of 'AndroidMediaNdkCapture'. Thus it's unaffected by this change set.

However, with #26627 in place, line 184 can be changed to directly capture BGR4 avoiding the conversion step in line 187.

If you modify the code to read from a file instead from a camera, then you will see the bug reported in #26616 and the effect of this patch.

Please also take a look on https://github.com/opencv/opencv/blob/4.x/samples/android/video-recorder/src/org/opencv/samples/recorder/RecorderActivity.java. Looks like we need to set proper output fourcc and drop cvtColor before imwrite.

My understanding is that that video capturers should output frames in BGR format, so it appears there is a bug in my original implementation for Android.

@asmorkalov : The recorder sample is affected. I will have look at it on weekend...